Enhancement of spin transfer torque magnetoresistive random access memory device using hydrogen plasma

Abstract

A method of making a MRAM device includes forming a magnetic tunnel junction on an electrode, the magnetic tunnel junction comprising a reference layer positioned in contact with the electrode, a tunnel barrier layer arranged on the reference layer, and a free layer arranged on the tunnel barrier layer; and depositing an encapsulating layer on and along sidewalls of the magnetic tunnel junction; wherein the exposing of the magnetic tunnel junction to hydrogen plasma is performed at a temperature from about 150 to about 250° C. An MRAM device including an encapsulating layer comprising either silicon nitride or aluminum oxide is also provided.

What is claimed is: 
     
         1 . A method of making a magnetic random access memory (MRAM) device, the method comprising:
 forming a magnetic tunnel junction on an electrode, the magnetic tunnel junction comprising a reference layer positioned in contact with the electrode, a tunnel barrier layer arranged on the reference layer, and a free layer arranged on the tunnel barrier layer;   exposing the magnetic tunnel junction to hydrogen plasma; and   depositing an encapsulating layer on and along sidewalls of the magnetic tunnel junction.   
     
     
         2 . The method of  claim 1 , wherein exposing the magnetic tunnel junction to hydrogen plasma includes employing a power in a range from about 25 to about 1000 Watts (W), or from about 25 to about 400 W. 
     
     
         3 . The method of  claim 1 , wherein exposing the magnetic tunnel junction to hydrogen plasma occurs at a temperature range from about 100 to about 400° C., or from about 125 to about 300° C., or from about 150 to about 250° C. 
     
     
         4 . The method of  claim 1 , wherein exposing the magnetic tunnel junction to hydrogen plasma occurs at a hydrogen pressure from about 1 to about 8 Torr, or from about 1.3 to about 4 Torr, or from about 1.5 to about 2 Torr. 
     
     
         5 . The method of  claim 1 , wherein exposing the magnetic tunnel junction to hydrogen plasma occurs at a hydrogen flow from about 200 to about 1400 standard cubic centimeters per minute (sccm), or from about 600 to about 1200 sccm, or from about 800 to about 1000 sccm. 
     
     
         6 . The method of  claim 1 , wherein exposing the magnetic tunnel junction to hydrogen plasma occurs over an exposure time of from about 5 to about 200 seconds, or from about 5 to about 100 seconds, or from about 10 to about 20 seconds. 
     
     
         7 . The method of  claim 1 , wherein the depositing the encapsulating layer comprises depositing by ion-beam deposition. 
     
     
         8 . The method of  claim 1 , wherein depositing the encapsulating layer comprises depositing by plasma enhanced chemical vapor deposition. 
     
     
         9 . The method of  claim 8 , wherein the chemical vapor deposition is performed at a temperature range from about 100 to about 250° C., or from about 150 to about 200° C. 
     
     
         10 . The method of  claim 1 , wherein depositing the encapsulating layer comprises depositing by physical vapor deposition. 
     
     
         11 . The method of  claim 1 , wherein the encapsulating layer is deposited by a combination of one or more of ion beam deposition, plasma-enhanced chemical vapor deposition, or physical vapor deposition. 
     
     
         12 . The method of  claim 10 , wherein the physical vapor deposition is performed at a temperature range from about 20 to about 25° C., or at room temperature. 
     
     
         13 . The method of  claim 1 , wherein the encapsulating layer comprises silicon nitride, aluminum oxide, or a combination thereof. 
     
     
         14 . The method of  claim 1 , wherein the encapsulating layer comprises silicon nitride. 
     
     
         15 . The method of  claim 1 , wherein the MRAM device is a spin torque transfer MRAM (STT-MRAM) device. 
     
     
         16 . A method of making a magnetic random access memory device, the method comprising:
 forming a magnetic tunnel junction on an electrode, the magnetic tunnel junction comprising either a free layer positioned in contact with the electrode, a tunnel barrier layer arranged on the free layer, and a reference layer arranged on the tunnel barrier layer, or a first reference layer positioned in contact with the electrode, a free layer arranged on the first reference layer, and a second reference layer arranged on the free layer; and   exposing the magnetic tunnel junction to hydrogen plasma; and   depositing an encapsulating layer on and along sidewalls of the magnetic tunnel junction.   
     
     
         17 . The method of  claim 16 , wherein the encapsulating layer comprises silicon nitride and is deposited by a PVD process. 
     
     
         18 . The method of  claim 16 , wherein the exposing of the magnetic tunnel junction to hydrogen plasma is performed with a power from about 25 Watts to about 400 Watts, at a temperature from about 150 to about 250° C., at a hydrogen pressure from about 1.5 to about 2 Torr, with a hydrogen flow from about 800 to about 1000 standard cubic centimeters per minute, for an exposure time from about 10 to about 20 seconds 
     
     
         19 . An MRAM device comprising a magnetic tunnel junction on an electrode, and an encapsulating layer deposited on along sidewalls of the magnetic tunnel junction;
 the magnetic tunnel junction comprising a reference layer positioned in contact with the electrode, a tunnel barrier layer arranged on the reference layer, and a free layer arranged on the tunnel barrier layer;   the encapsulating layer comprising either silicon nitride or aluminum oxide; and   wherein the MRAM device has a spin torque switching efficiency improvement of 5-20% compared to a similar device made without hydrogen plasma treatment.   
     
     
         20 . The MRAM device according to  claim 19 , wherein the encapsulating layer comprises silicon nitride and is deposited by a PVD process.